define(function(require, exports, module) {
//     Underscore.js 1.7.0
//     http://underscorejs.org
//     (c) 2009-2014 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
//     Underscore may be freely distributed under the MIT license.

    (function() {

        // Baseline setup
        // --------------

        // Establish the root object, `window` in the browser, or `exports` on the server.
        var root = this;

        // Save the previous value of the `_` variable.
        var previousUnderscore = root._;

        // Save bytes in the minified (but not gzipped) version:
        var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;

        // Create quick reference variables for speed access to core prototypes.
        var
            push             = ArrayProto.push,
            slice            = ArrayProto.slice,
            concat           = ArrayProto.concat,
            toString         = ObjProto.toString,
            hasOwnProperty   = ObjProto.hasOwnProperty;

        // All **ECMAScript 5** native function implementations that we hope to use
        // are declared here.
        var
            nativeIsArray      = Array.isArray,
            nativeKeys         = Object.keys,
            nativeBind         = FuncProto.bind;

        // Create a safe reference to the Underscore object for use below.
        var _ = function(obj) {
            if (obj instanceof _) return obj;
            if (!(this instanceof _)) return new _(obj);
            this._wrapped = obj;
        };

        // Export the Underscore object for **Node.js**, with
        // backwards-compatibility for the old `require()` API. If we're in
        // the browser, add `_` as a global object.
        if (typeof exports !== 'undefined') {
            if (typeof module !== 'undefined' && module.exports) {
                exports = module.exports = _;
            }
            exports._ = _;
        } else {
            root._ = _;
        }

        // Current version.
        _.VERSION = '1.7.0';

        // Internal function that returns an efficient (for current engines) version
        // of the passed-in callback, to be repeatedly applied in other Underscore
        // functions.
        var createCallback = function(func, context, argCount) {
            if (context === void 0) return func;
            switch (argCount == null ? 3 : argCount) {
                case 1: return function(value) {
                    return func.call(context, value);
                };
                case 2: return function(value, other) {
                    return func.call(context, value, other);
                };
                case 3: return function(value, index, collection) {
                    return func.call(context, value, index, collection);
                };
                case 4: return function(accumulator, value, index, collection) {
                    return func.call(context, accumulator, value, index, collection);
                };
            }
            return function() {
                return func.apply(context, arguments);
            };
        };

        // A mostly-internal function to generate callbacks that can be applied
        // to each element in a collection, returning the desired result — either
        // identity, an arbitrary callback, a property matcher, or a property accessor.
        _.iteratee = function(value, context, argCount) {
            if (value == null) return _.identity;
            if (_.isFunction(value)) return createCallback(value, context, argCount);
            if (_.isObject(value)) return _.matches(value);
            return _.property(value);
        };

        // Collection Functions
        // --------------------

        // The cornerstone, an `each` implementation, aka `forEach`.
        // Handles raw objects in addition to array-likes. Treats all
        // sparse array-likes as if they were dense.
        _.each = _.forEach = function(obj, iteratee, context) {
            if (obj == null) return obj;
            iteratee = createCallback(iteratee, context);
            var i, length = obj.length;
            if (length === +length) {
                for (i = 0; i < length; i++) {
                    iteratee(obj[i], i, obj);
                }
            } else {
                var keys = _.keys(obj);
                for (i = 0, length = keys.length; i < length; i++) {
                    iteratee(obj[keys[i]], keys[i], obj);
                }
            }
            return obj;
        };

        // Return the results of applying the iteratee to each element.
        _.map = _.collect = function(obj, iteratee, context) {
            if (obj == null) return [];
            iteratee = _.iteratee(iteratee, context);
            var keys = obj.length !== +obj.length && _.keys(obj),
                length = (keys || obj).length,
                results = Array(length),
                currentKey;
            for (var index = 0; index < length; index++) {
                currentKey = keys ? keys[index] : index;
                results[index] = iteratee(obj[currentKey], currentKey, obj);
            }
            return results;
        };

        var reduceError = 'Reduce of empty array with no initial value';

        // **Reduce** builds up a single result from a list of values, aka `inject`,
        // or `foldl`.
        _.reduce = _.foldl = _.inject = function(obj, iteratee, memo, context) {
            if (obj == null) obj = [];
            iteratee = createCallback(iteratee, context, 4);
            var keys = obj.length !== +obj.length && _.keys(obj),
                length = (keys || obj).length,
                index = 0, currentKey;
            if (arguments.length < 3) {
                if (!length) throw new TypeError(reduceError);
                memo = obj[keys ? keys[index++] : index++];
            }
            for (; index < length; index++) {
                currentKey = keys ? keys[index] : index;
                memo = iteratee(memo, obj[currentKey], currentKey, obj);
            }
            return memo;
        };

        // The right-associative version of reduce, also known as `foldr`.
        _.reduceRight = _.foldr = function(obj, iteratee, memo, context) {
            if (obj == null) obj = [];
            iteratee = createCallback(iteratee, context, 4);
            var keys = obj.length !== + obj.length && _.keys(obj),
                index = (keys || obj).length,
                currentKey;
            if (arguments.length < 3) {
                if (!index) throw new TypeError(reduceError);
                memo = obj[keys ? keys[--index] : --index];
            }
            while (index--) {
                currentKey = keys ? keys[index] : index;
                memo = iteratee(memo, obj[currentKey], currentKey, obj);
            }
            return memo;
        };

        // Return the first value which passes a truth test. Aliased as `detect`.
        _.find = _.detect = function(obj, predicate, context) {
            var result;
            predicate = _.iteratee(predicate, context);
            _.some(obj, function(value, index, list) {
                if (predicate(value, index, list)) {
                    result = value;
                    return true;
                }
            });
            return result;
        };

        // Return all the elements that pass a truth test.
        // Aliased as `select`.
        _.filter = _.select = function(obj, predicate, context) {
            var results = [];
            if (obj == null) return results;
            predicate = _.iteratee(predicate, context);
            _.each(obj, function(value, index, list) {
                if (predicate(value, index, list)) results.push(value);
            });
            return results;
        };

        // Return all the elements for which a truth test fails.
        _.reject = function(obj, predicate, context) {
            return _.filter(obj, _.negate(_.iteratee(predicate)), context);
        };

        // Determine whether all of the elements match a truth test.
        // Aliased as `all`.
        _.every = _.all = function(obj, predicate, context) {
            if (obj == null) return true;
            predicate = _.iteratee(predicate, context);
            var keys = obj.length !== +obj.length && _.keys(obj),
                length = (keys || obj).length,
                index, currentKey;
            for (index = 0; index < length; index++) {
                currentKey = keys ? keys[index] : index;
                if (!predicate(obj[currentKey], currentKey, obj)) return false;
            }
            return true;
        };

        // Determine if at least one element in the object matches a truth test.
        // Aliased as `any`.
        _.some = _.any = function(obj, predicate, context) {
            if (obj == null) return false;
            predicate = _.iteratee(predicate, context);
            var keys = obj.length !== +obj.length && _.keys(obj),
                length = (keys || obj).length,
                index, currentKey;
            for (index = 0; index < length; index++) {
                currentKey = keys ? keys[index] : index;
                if (predicate(obj[currentKey], currentKey, obj)) return true;
            }
            return false;
        };

        // Determine if the array or object contains a given value (using `===`).
        // Aliased as `include`.
        _.contains = _.include = function(obj, target) {
            if (obj == null) return false;
            if (obj.length !== +obj.length) obj = _.values(obj);
            return _.indexOf(obj, target) >= 0;
        };

        // Invoke a method (with arguments) on every item in a collection.
        _.invoke = function(obj, method) {
            var args = slice.call(arguments, 2);
            var isFunc = _.isFunction(method);
            return _.map(obj, function(value) {
                return (isFunc ? method : value[method]).apply(value, args);
            });
        };

        // Convenience version of a common use case of `map`: fetching a property.
        _.pluck = function(obj, key) {
            return _.map(obj, _.property(key));
        };

        // Convenience version of a common use case of `filter`: selecting only objects
        // containing specific `key:value` pairs.
        _.where = function(obj, attrs) {
            return _.filter(obj, _.matches(attrs));
        };

        // Convenience version of a common use case of `find`: getting the first object
        // containing specific `key:value` pairs.
        _.findWhere = function(obj, attrs) {
            return _.find(obj, _.matches(attrs));
        };

        // Return the maximum element (or element-based computation).
        _.max = function(obj, iteratee, context) {
            var result = -Infinity, lastComputed = -Infinity,
                value, computed;
            if (iteratee == null && obj != null) {
                obj = obj.length === +obj.length ? obj : _.values(obj);
                for (var i = 0, length = obj.length; i < length; i++) {
                    value = obj[i];
                    if (value > result) {
                        result = value;
                    }
                }
            } else {
                iteratee = _.iteratee(iteratee, context);
                _.each(obj, function(value, index, list) {
                    computed = iteratee(value, index, list);
                    if (computed > lastComputed || computed === -Infinity && result === -Infinity) {
                        result = value;
                        lastComputed = computed;
                    }
                });
            }
            return result;
        };

        // Return the minimum element (or element-based computation).
        _.min = function(obj, iteratee, context) {
            var result = Infinity, lastComputed = Infinity,
                value, computed;
            if (iteratee == null && obj != null) {
                obj = obj.length === +obj.length ? obj : _.values(obj);
                for (var i = 0, length = obj.length; i < length; i++) {
                    value = obj[i];
                    if (value < result) {
                        result = value;
                    }
                }
            } else {
                iteratee = _.iteratee(iteratee, context);
                _.each(obj, function(value, index, list) {
                    computed = iteratee(value, index, list);
                    if (computed < lastComputed || computed === Infinity && result === Infinity) {
                        result = value;
                        lastComputed = computed;
                    }
                });
            }
            return result;
        };

        // Shuffle a collection, using the modern version of the
        // [Fisher-Yates shuffle](http://en.wikipedia.org/wiki/Fisher–Yates_shuffle).
        _.shuffle = function(obj) {
            var set = obj && obj.length === +obj.length ? obj : _.values(obj);
            var length = set.length;
            var shuffled = Array(length);
            for (var index = 0, rand; index < length; index++) {
                rand = _.random(0, index);
                if (rand !== index) shuffled[index] = shuffled[rand];
                shuffled[rand] = set[index];
            }
            return shuffled;
        };

        // Sample **n** random values from a collection.
        // If **n** is not specified, returns a single random element.
        // The internal `guard` argument allows it to work with `map`.
        _.sample = function(obj, n, guard) {
            if (n == null || guard) {
                if (obj.length !== +obj.length) obj = _.values(obj);
                return obj[_.random(obj.length - 1)];
            }
            return _.shuffle(obj).slice(0, Math.max(0, n));
        };

        // Sort the object's values by a criterion produced by an iteratee.
        _.sortBy = function(obj, iteratee, context) {
            iteratee = _.iteratee(iteratee, context);
            return _.pluck(_.map(obj, function(value, index, list) {
                return {
                    value: value,
                    index: index,
                    criteria: iteratee(value, index, list)
                };
            }).sort(function(left, right) {
                var a = left.criteria;
                var b = right.criteria;
                if (a !== b) {
                    if (a > b || a === void 0) return 1;
                    if (a < b || b === void 0) return -1;
                }
                return left.index - right.index;
            }), 'value');
        };

        // An internal function used for aggregate "group by" operations.
        var group = function(behavior) {
            return function(obj, iteratee, context) {
                var result = {};
                iteratee = _.iteratee(iteratee, context);
                _.each(obj, function(value, index) {
                    var key = iteratee(value, index, obj);
                    behavior(result, value, key);
                });
                return result;
            };
        };

        // Groups the object's values by a criterion. Pass either a string attribute
        // to group by, or a function that returns the criterion.
        _.groupBy = group(function(result, value, key) {
            if (_.has(result, key)) result[key].push(value); else result[key] = [value];
        });

        // Indexes the object's values by a criterion, similar to `groupBy`, but for
        // when you know that your index values will be unique.
        _.indexBy = group(function(result, value, key) {
            result[key] = value;
        });

        // Counts instances of an object that group by a certain criterion. Pass
        // either a string attribute to count by, or a function that returns the
        // criterion.
        _.countBy = group(function(result, value, key) {
            if (_.has(result, key)) result[key]++; else result[key] = 1;
        });

        // Use a comparator function to figure out the smallest index at which
        // an object should be inserted so as to maintain order. Uses binary search.
        _.sortedIndex = function(array, obj, iteratee, context) {
            iteratee = _.iteratee(iteratee, context, 1);
            var value = iteratee(obj);
            var low = 0, high = array.length;
            while (low < high) {
                var mid = low + high >>> 1;
                if (iteratee(array[mid]) < value) low = mid + 1; else high = mid;
            }
            return low;
        };

        // Safely create a real, live array from anything iterable.
        _.toArray = function(obj) {
            if (!obj) return [];
            if (_.isArray(obj)) return slice.call(obj);
            if (obj.length === +obj.length) return _.map(obj, _.identity);
            return _.values(obj);
        };

        // Return the number of elements in an object.
        _.size = function(obj) {
            if (obj == null) return 0;
            return obj.length === +obj.length ? obj.length : _.keys(obj).length;
        };

        // Split a collection into two arrays: one whose elements all satisfy the given
        // predicate, and one whose elements all do not satisfy the predicate.
        _.partition = function(obj, predicate, context) {
            predicate = _.iteratee(predicate, context);
            var pass = [], fail = [];
            _.each(obj, function(value, key, obj) {
                (predicate(value, key, obj) ? pass : fail).push(value);
            });
            return [pass, fail];
        };

        // Array Functions
        // ---------------

        // Get the first element of an array. Passing **n** will return the first N
        // values in the array. Aliased as `head` and `take`. The **guard** check
        // allows it to work with `_.map`.
        _.first = _.head = _.take = function(array, n, guard) {
            if (array == null) return void 0;
            if (n == null || guard) return array[0];
            if (n < 0) return [];
            return slice.call(array, 0, n);
        };

        // Returns everything but the last entry of the array. Especially useful on
        // the arguments object. Passing **n** will return all the values in
        // the array, excluding the last N. The **guard** check allows it to work with
        // `_.map`.
        _.initial = function(array, n, guard) {
            return slice.call(array, 0, Math.max(0, array.length - (n == null || guard ? 1 : n)));
        };

        // Get the last element of an array. Passing **n** will return the last N
        // values in the array. The **guard** check allows it to work with `_.map`.
        _.last = function(array, n, guard) {
            if (array == null) return void 0;
            if (n == null || guard) return array[array.length - 1];
            return slice.call(array, Math.max(array.length - n, 0));
        };

        // Returns everything but the first entry of the array. Aliased as `tail` and `drop`.
        // Especially useful on the arguments object. Passing an **n** will return
        // the rest N values in the array. The **guard**
        // check allows it to work with `_.map`.
        _.rest = _.tail = _.drop = function(array, n, guard) {
            return slice.call(array, n == null || guard ? 1 : n);
        };

        // Trim out all falsy values from an array.
        _.compact = function(array) {
            return _.filter(array, _.identity);
        };

        // Internal implementation of a recursive `flatten` function.
        var flatten = function(input, shallow, strict, output) {
            if (shallow && _.every(input, _.isArray)) {
                return concat.apply(output, input);
            }
            for (var i = 0, length = input.length; i < length; i++) {
                var value = input[i];
                if (!_.isArray(value) && !_.isArguments(value)) {
                    if (!strict) output.push(value);
                } else if (shallow) {
                    push.apply(output, value);
                } else {
                    flatten(value, shallow, strict, output);
                }
            }
            return output;
        };

        // Flatten out an array, either recursively (by default), or just one level.
        _.flatten = function(array, shallow) {
            return flatten(array, shallow, false, []);
        };

        // Return a version of the array that does not contain the specified value(s).
        _.without = function(array) {
            return _.difference(array, slice.call(arguments, 1));
        };

        // Produce a duplicate-free version of the array. If the array has already
        // been sorted, you have the option of using a faster algorithm.
        // Aliased as `unique`.
        _.uniq = _.unique = function(array, isSorted, iteratee, context) {
            if (array == null) return [];
            if (!_.isBoolean(isSorted)) {
                context = iteratee;
                iteratee = isSorted;
                isSorted = false;
            }
            if (iteratee != null) iteratee = _.iteratee(iteratee, context);
            var result = [];
            var seen = [];
            for (var i = 0, length = array.length; i < length; i++) {
                var value = array[i];
                if (isSorted) {
                    if (!i || seen !== value) result.push(value);
                    seen = value;
                } else if (iteratee) {
                    var computed = iteratee(value, i, array);
                    if (_.indexOf(seen, computed) < 0) {
                        seen.push(computed);
                        result.push(value);
                    }
                } else if (_.indexOf(result, value) < 0) {
                    result.push(value);
                }
            }
            return result;
        };

        // Produce an array that contains the union: each distinct element from all of
        // the passed-in arrays.
        _.union = function() {
            return _.uniq(flatten(arguments, true, true, []));
        };

        // Produce an array that contains every item shared between all the
        // passed-in arrays.
        _.intersection = function(array) {
            if (array == null) return [];
            var result = [];
            var argsLength = arguments.length;
            for (var i = 0, length = array.length; i < length; i++) {
                var item = array[i];
                if (_.contains(result, item)) continue;
                for (var j = 1; j < argsLength; j++) {
                    if (!_.contains(arguments[j], item)) break;
                }
                if (j === argsLength) result.push(item);
            }
            return result;
        };

        // Take the difference between one array and a number of other arrays.
        // Only the elements present in just the first array will remain.
        _.difference = function(array) {
            var rest = flatten(slice.call(arguments, 1), true, true, []);
            return _.filter(array, function(value){
                return !_.contains(rest, value);
            });
        };

        // Zip together multiple lists into a single array -- elements that share
        // an index go together.
        _.zip = function(array) {
            if (array == null) return [];
            var length = _.max(arguments, 'length').length;
            var results = Array(length);
            for (var i = 0; i < length; i++) {
                results[i] = _.pluck(arguments, i);
            }
            return results;
        };

        // Converts lists into objects. Pass either a single array of `[key, value]`
        // pairs, or two parallel arrays of the same length -- one of keys, and one of
        // the corresponding values.
        _.object = function(list, values) {
            if (list == null) return {};
            var result = {};
            for (var i = 0, length = list.length; i < length; i++) {
                if (values) {
                    result[list[i]] = values[i];
                } else {
                    result[list[i][0]] = list[i][1];
                }
            }
            return result;
        };

        // Return the position of the first occurrence of an item in an array,
        // or -1 if the item is not included in the array.
        // If the array is large and already in sort order, pass `true`
        // for **isSorted** to use binary search.
        _.indexOf = function(array, item, isSorted) {
            if (array == null) return -1;
            var i = 0, length = array.length;
            if (isSorted) {
                if (typeof isSorted == 'number') {
                    i = isSorted < 0 ? Math.max(0, length + isSorted) : isSorted;
                } else {
                    i = _.sortedIndex(array, item);
                    return array[i] === item ? i : -1;
                }
            }
            for (; i < length; i++) if (array[i] === item) return i;
            return -1;
        };

        _.lastIndexOf = function(array, item, from) {
            if (array == null) return -1;
            var idx = array.length;
            if (typeof from == 'number') {
                idx = from < 0 ? idx + from + 1 : Math.min(idx, from + 1);
            }
            while (--idx >= 0) if (array[idx] === item) return idx;
            return -1;
        };

        // Generate an integer Array containing an arithmetic progression. A port of
        // the native Python `range()` function. See
        // [the Python documentation](http://docs.python.org/library/functions.html#range).
        _.range = function(start, stop, step) {
            if (arguments.length <= 1) {
                stop = start || 0;
                start = 0;
            }
            step = step || 1;

            var length = Math.max(Math.ceil((stop - start) / step), 0);
            var range = Array(length);

            for (var idx = 0; idx < length; idx++, start += step) {
                range[idx] = start;
            }

            return range;
        };

        // Function (ahem) Functions
        // ------------------

        // Reusable constructor function for prototype setting.
        var Ctor = function(){};

        // Create a function bound to a given object (assigning `this`, and arguments,
        // optionally). Delegates to **ECMAScript 5**'s native `Function.bind` if
        // available.
        _.bind = function(func, context) {
            var args, bound;
            if (nativeBind && func.bind === nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
            if (!_.isFunction(func)) throw new TypeError('Bind must be called on a function');
            args = slice.call(arguments, 2);
            bound = function() {
                if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
                Ctor.prototype = func.prototype;
                var self = new Ctor;
                Ctor.prototype = null;
                var result = func.apply(self, args.concat(slice.call(arguments)));
                if (_.isObject(result)) return result;
                return self;
            };
            return bound;
        };

        // Partially apply a function by creating a version that has had some of its
        // arguments pre-filled, without changing its dynamic `this` context. _ acts
        // as a placeholder, allowing any combination of arguments to be pre-filled.
        _.partial = function(func) {
            var boundArgs = slice.call(arguments, 1);
            return function() {
                var position = 0;
                var args = boundArgs.slice();
                for (var i = 0, length = args.length; i < length; i++) {
                    if (args[i] === _) args[i] = arguments[position++];
                }
                while (position < arguments.length) args.push(arguments[position++]);
                return func.apply(this, args);
            };
        };

        // Bind a number of an object's methods to that object. Remaining arguments
        // are the method names to be bound. Useful for ensuring that all callbacks
        // defined on an object belong to it.
        _.bindAll = function(obj) {
            var i, length = arguments.length, key;
            if (length <= 1) throw new Error('bindAll must be passed function names');
            for (i = 1; i < length; i++) {
                key = arguments[i];
                obj[key] = _.bind(obj[key], obj);
            }
            return obj;
        };

        // Memoize an expensive function by storing its results.
        _.memoize = function(func, hasher) {
            var memoize = function(key) {
                var cache = memoize.cache;
                var address = hasher ? hasher.apply(this, arguments) : key;
                if (!_.has(cache, address)) cache[address] = func.apply(this, arguments);
                return cache[address];
            };
            memoize.cache = {};
            return memoize;
        };

        // Delays a function for the given number of milliseconds, and then calls
        // it with the arguments supplied.
        _.delay = function(func, wait) {
            var args = slice.call(arguments, 2);
            return setTimeout(function(){
                return func.apply(null, args);
            }, wait);
        };

        // Defers a function, scheduling it to run after the current call stack has
        // cleared.
        _.defer = function(func) {
            return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
        };

        // Returns a function, that, when invoked, will only be triggered at most once
        // during a given window of time. Normally, the throttled function will run
        // as much as it can, without ever going more than once per `wait` duration;
        // but if you'd like to disable the execution on the leading edge, pass
        // `{leading: false}`. To disable execution on the trailing edge, ditto.
        _.throttle = function(func, wait, options) {
            var context, args, result;
            var timeout = null;
            var previous = 0;
            if (!options) options = {};
            var later = function() {
                previous = options.leading === false ? 0 : _.now();
                timeout = null;
                result = func.apply(context, args);
                if (!timeout) context = args = null;
            };
            return function() {
                var now = _.now();
                if (!previous && options.leading === false) previous = now;
                var remaining = wait - (now - previous);
                context = this;
                args = arguments;
                if (remaining <= 0 || remaining > wait) {
                    clearTimeout(timeout);
                    timeout = null;
                    previous = now;
                    result = func.apply(context, args);
                    if (!timeout) context = args = null;
                } else if (!timeout && options.trailing !== false) {
                    timeout = setTimeout(later, remaining);
                }
                return result;
            };
        };

        // Returns a function, that, as long as it continues to be invoked, will not
        // be triggered. The function will be called after it stops being called for
        // N milliseconds. If `immediate` is passed, trigger the function on the
        // leading edge, instead of the trailing.
        _.debounce = function(func, wait, immediate) {
            var timeout, args, context, timestamp, result;

            var later = function() {
                var last = _.now() - timestamp;

                if (last < wait && last > 0) {
                    timeout = setTimeout(later, wait - last);
                } else {
                    timeout = null;
                    if (!immediate) {
                        result = func.apply(context, args);
                        if (!timeout) context = args = null;
                    }
                }
            };

            return function() {
                context = this;
                args = arguments;
                timestamp = _.now();
                var callNow = immediate && !timeout;
                if (!timeout) timeout = setTimeout(later, wait);
                if (callNow) {
                    result = func.apply(context, args);
                    context = args = null;
                }

                return result;
            };
        };

        // Returns the first function passed as an argument to the second,
        // allowing you to adjust arguments, run code before and after, and
        // conditionally execute the original function.
        _.wrap = function(func, wrapper) {
            return _.partial(wrapper, func);
        };

        // Returns a negated version of the passed-in predicate.
        _.negate = function(predicate) {
            return function() {
                return !predicate.apply(this, arguments);
            };
        };

        // Returns a function that is the composition of a list of functions, each
        // consuming the return value of the function that follows.
        _.compose = function() {
            var args = arguments;
            var start = args.length - 1;
            return function() {
                var i = start;
                var result = args[start].apply(this, arguments);
                while (i--) result = args[i].call(this, result);
                return result;
            };
        };

        // Returns a function that will only be executed after being called N times.
        _.after = function(times, func) {
            return function() {
                if (--times < 1) {
                    return func.apply(this, arguments);
                }
            };
        };

        // Returns a function that will only be executed before being called N times.
        _.before = function(times, func) {
            var memo;
            return function() {
                if (--times > 0) {
                    memo = func.apply(this, arguments);
                } else {
                    func = null;
                }
                return memo;
            };
        };

        // Returns a function that will be executed at most one time, no matter how
        // often you call it. Useful for lazy initialization.
        _.once = _.partial(_.before, 2);

        // Object Functions
        // ----------------

        // Retrieve the names of an object's properties.
        // Delegates to **ECMAScript 5**'s native `Object.keys`
        _.keys = function(obj) {
            if (!_.isObject(obj)) return [];
            if (nativeKeys) return nativeKeys(obj);
            var keys = [];
            for (var key in obj) if (_.has(obj, key)) keys.push(key);
            return keys;
        };

        // Retrieve the values of an object's properties.
        _.values = function(obj) {
            var keys = _.keys(obj);
            var length = keys.length;
            var values = Array(length);
            for (var i = 0; i < length; i++) {
                values[i] = obj[keys[i]];
            }
            return values;
        };

        // Convert an object into a list of `[key, value]` pairs.
        _.pairs = function(obj) {
            var keys = _.keys(obj);
            var length = keys.length;
            var pairs = Array(length);
            for (var i = 0; i < length; i++) {
                pairs[i] = [keys[i], obj[keys[i]]];
            }
            return pairs;
        };

        // Invert the keys and values of an object. The values must be serializable.
        _.invert = function(obj) {
            var result = {};
            var keys = _.keys(obj);
            for (var i = 0, length = keys.length; i < length; i++) {
                result[obj[keys[i]]] = keys[i];
            }
            return result;
        };

        // Return a sorted list of the function names available on the object.
        // Aliased as `methods`
        _.functions = _.methods = function(obj) {
            var names = [];
            for (var key in obj) {
                if (_.isFunction(obj[key])) names.push(key);
            }
            return names.sort();
        };

        // Extend a given object with all the properties in passed-in object(s).
        _.extend = function(obj) {
            if (!_.isObject(obj)) return obj;
            var source, prop;
            for (var i = 1, length = arguments.length; i < length; i++) {
                source = arguments[i];
                for (prop in source) {
                    if (hasOwnProperty.call(source, prop)) {
                        obj[prop] = source[prop];
                    }
                }
            }
            return obj;
        };

        // Return a copy of the object only containing the whitelisted properties.
        _.pick = function(obj, iteratee, context) {
            var result = {}, key;
            if (obj == null) return result;
            if (_.isFunction(iteratee)) {
                iteratee = createCallback(iteratee, context);
                for (key in obj) {
                    var value = obj[key];
                    if (iteratee(value, key, obj)) result[key] = value;
                }
            } else {
                var keys = concat.apply([], slice.call(arguments, 1));
                obj = new Object(obj);
                for (var i = 0, length = keys.length; i < length; i++) {
                    key = keys[i];
                    if (key in obj) result[key] = obj[key];
                }
            }
            return result;
        };

        // Return a copy of the object without the blacklisted properties.
        _.omit = function(obj, iteratee, context) {
            if (_.isFunction(iteratee)) {
                iteratee = _.negate(iteratee);
            } else {
                var keys = _.map(concat.apply([], slice.call(arguments, 1)), String);
                iteratee = function(value, key) {
                    return !_.contains(keys, key);
                };
            }
            return _.pick(obj, iteratee, context);
        };

        // Fill in a given object with default properties.
        _.defaults = function(obj) {
            if (!_.isObject(obj)) return obj;
            for (var i = 1, length = arguments.length; i < length; i++) {
                var source = arguments[i];
                for (var prop in source) {
                    if (obj[prop] === void 0) obj[prop] = source[prop];
                }
            }
            return obj;
        };

        // Create a (shallow-cloned) duplicate of an object.
        _.clone = function(obj) {
            if (!_.isObject(obj)) return obj;
            return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
        };

        // Invokes interceptor with the obj, and then returns obj.
        // The primary purpose of this method is to "tap into" a method chain, in
        // order to perform operations on intermediate results within the chain.
        _.tap = function(obj, interceptor) {
            interceptor(obj);
            return obj;
        };

        // Internal recursive comparison function for `isEqual`.
        var eq = function(a, b, aStack, bStack) {
            // Identical objects are equal. `0 === -0`, but they aren't identical.
            // See the [Harmony `egal` proposal](http://wiki.ecmascript.org/doku.php?id=harmony:egal).
            if (a === b) return a !== 0 || 1 / a === 1 / b;
            // A strict comparison is necessary because `null == undefined`.
            if (a == null || b == null) return a === b;
            // Unwrap any wrapped objects.
            if (a instanceof _) a = a._wrapped;
            if (b instanceof _) b = b._wrapped;
            // Compare `[[Class]]` names.
            var className = toString.call(a);
            if (className !== toString.call(b)) return false;
            switch (className) {
                // Strings, numbers, regular expressions, dates, and booleans are compared by value.
                case '[object RegExp]':
                // RegExps are coerced to strings for comparison (Note: '' + /a/i === '/a/i')
                case '[object String]':
                    // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
                    // equivalent to `new String("5")`.
                    return '' + a === '' + b;
                case '[object Number]':
                    // `NaN`s are equivalent, but non-reflexive.
                    // Object(NaN) is equivalent to NaN
                    if (+a !== +a) return +b !== +b;
                    // An `egal` comparison is performed for other numeric values.
                    return +a === 0 ? 1 / +a === 1 / b : +a === +b;
                case '[object Date]':
                case '[object Boolean]':
                    // Coerce dates and booleans to numeric primitive values. Dates are compared by their
                    // millisecond representations. Note that invalid dates with millisecond representations
                    // of `NaN` are not equivalent.
                    return +a === +b;
            }
            if (typeof a != 'object' || typeof b != 'object') return false;
            // Assume equality for cyclic structures. The algorithm for detecting cyclic
            // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
            var length = aStack.length;
            while (length--) {
                // Linear search. Performance is inversely proportional to the number of
                // unique nested structures.
                if (aStack[length] === a) return bStack[length] === b;
            }
            // Objects with different constructors are not equivalent, but `Object`s
            // from different frames are.
            var aCtor = a.constructor, bCtor = b.constructor;
            if (
                aCtor !== bCtor &&
                // Handle Object.create(x) cases
                'constructor' in a && 'constructor' in b &&
                !(_.isFunction(aCtor) && aCtor instanceof aCtor &&
                    _.isFunction(bCtor) && bCtor instanceof bCtor)
                ) {
                return false;
            }
            // Add the first object to the stack of traversed objects.
            aStack.push(a);
            bStack.push(b);
            var size, result;
            // Recursively compare objects and arrays.
            if (className === '[object Array]') {
                // Compare array lengths to determine if a deep comparison is necessary.
                size = a.length;
                result = size === b.length;
                if (result) {
                    // Deep compare the contents, ignoring non-numeric properties.
                    while (size--) {
                        if (!(result = eq(a[size], b[size], aStack, bStack))) break;
                    }
                }
            } else {
                // Deep compare objects.
                var keys = _.keys(a), key;
                size = keys.length;
                // Ensure that both objects contain the same number of properties before comparing deep equality.
                result = _.keys(b).length === size;
                if (result) {
                    while (size--) {
                        // Deep compare each member
                        key = keys[size];
                        if (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) break;
                    }
                }
            }
            // Remove the first object from the stack of traversed objects.
            aStack.pop();
            bStack.pop();
            return result;
        };

        // Perform a deep comparison to check if two objects are equal.
        _.isEqual = function(a, b) {
            return eq(a, b, [], []);
        };

        // Is a given array, string, or object empty?
        // An "empty" object has no enumerable own-properties.
        _.isEmpty = function(obj) {
            if (obj == null) return true;
            if (_.isArray(obj) || _.isString(obj) || _.isArguments(obj)) return obj.length === 0;
            for (var key in obj) if (_.has(obj, key)) return false;
            return true;
        };

        // Is a given value a DOM element?
        _.isElement = function(obj) {
            return !!(obj && obj.nodeType === 1);
        };

        // Is a given value an array?
        // Delegates to ECMA5's native Array.isArray
        _.isArray = nativeIsArray || function(obj) {
            return toString.call(obj) === '[object Array]';
        };

        // Is a given variable an object?
        _.isObject = function(obj) {
            var type = typeof obj;
            return type === 'function' || type === 'object' && !!obj;
        };

        // Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp.
        _.each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp'], function(name) {
            _['is' + name] = function(obj) {
                return toString.call(obj) === '[object ' + name + ']';
            };
        });

        // Define a fallback version of the method in browsers (ahem, IE), where
        // there isn't any inspectable "Arguments" type.
        if (!_.isArguments(arguments)) {
            _.isArguments = function(obj) {
                return _.has(obj, 'callee');
            };
        }

        // Optimize `isFunction` if appropriate. Work around an IE 11 bug.
        if (typeof /./ !== 'function') {
            _.isFunction = function(obj) {
                return typeof obj == 'function' || false;
            };
        }

        // Is a given object a finite number?
        _.isFinite = function(obj) {
            return isFinite(obj) && !isNaN(parseFloat(obj));
        };

        // Is the given value `NaN`? (NaN is the only number which does not equal itself).
        _.isNaN = function(obj) {
            return _.isNumber(obj) && obj !== +obj;
        };

        // Is a given value a boolean?
        _.isBoolean = function(obj) {
            return obj === true || obj === false || toString.call(obj) === '[object Boolean]';
        };

        // Is a given value equal to null?
        _.isNull = function(obj) {
            return obj === null;
        };

        // Is a given variable undefined?
        _.isUndefined = function(obj) {
            return obj === void 0;
        };

        // Shortcut function for checking if an object has a given property directly
        // on itself (in other words, not on a prototype).
        _.has = function(obj, key) {
            return obj != null && hasOwnProperty.call(obj, key);
        };

        // Utility Functions
        // -----------------

        // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
        // previous owner. Returns a reference to the Underscore object.
        _.noConflict = function() {
            root._ = previousUnderscore;
            return this;
        };

        // Keep the identity function around for default iteratees.
        _.identity = function(value) {
            return value;
        };

        // Predicate-generating functions. Often useful outside of Underscore.
        _.constant = function(value) {
            return function() {
                return value;
            };
        };

        _.noop = function(){};

        _.property = function(key) {
            return function(obj) {
                return obj[key];
            };
        };

        // Returns a predicate for checking whether an object has a given set of `key:value` pairs.
        _.matches = function(attrs) {
            var pairs = _.pairs(attrs), length = pairs.length;
            return function(obj) {
                if (obj == null) return !length;
                obj = new Object(obj);
                for (var i = 0; i < length; i++) {
                    var pair = pairs[i], key = pair[0];
                    if (pair[1] !== obj[key] || !(key in obj)) return false;
                }
                return true;
            };
        };

        // Run a function **n** times.
        _.times = function(n, iteratee, context) {
            var accum = Array(Math.max(0, n));
            iteratee = createCallback(iteratee, context, 1);
            for (var i = 0; i < n; i++) accum[i] = iteratee(i);
            return accum;
        };

        // Return a random integer between min and max (inclusive).
        _.random = function(min, max) {
            if (max == null) {
                max = min;
                min = 0;
            }
            return min + Math.floor(Math.random() * (max - min + 1));
        };

        // A (possibly faster) way to get the current timestamp as an integer.
        _.now = Date.now || function() {
            return new Date().getTime();
        };

        // List of HTML entities for escaping.
        var escapeMap = {
            '&': '&amp;',
            '<': '&lt;',
            '>': '&gt;',
            '"': '&quot;',
            "'": '&#x27;',
            '`': '&#x60;'
        };
        var unescapeMap = _.invert(escapeMap);

        // Functions for escaping and unescaping strings to/from HTML interpolation.
        var createEscaper = function(map) {
            var escaper = function(match) {
                return map[match];
            };
            // Regexes for identifying a key that needs to be escaped
            var source = '(?:' + _.keys(map).join('|') + ')';
            var testRegexp = RegExp(source);
            var replaceRegexp = RegExp(source, 'g');
            return function(string) {
                string = string == null ? '' : '' + string;
                return testRegexp.test(string) ? string.replace(replaceRegexp, escaper) : string;
            };
        };
        _.escape = createEscaper(escapeMap);
        _.unescape = createEscaper(unescapeMap);

        // If the value of the named `property` is a function then invoke it with the
        // `object` as context; otherwise, return it.
        _.result = function(object, property) {
            if (object == null) return void 0;
            var value = object[property];
            return _.isFunction(value) ? object[property]() : value;
        };

        // Generate a unique integer id (unique within the entire client session).
        // Useful for temporary DOM ids.
        var idCounter = 0;
        _.uniqueId = function(prefix) {
            var id = ++idCounter + '';
            return prefix ? prefix + id : id;
        };

        // By default, Underscore uses ERB-style template delimiters, change the
        // following template settings to use alternative delimiters.
        _.templateSettings = {
            evaluate    : /<%([\s\S]+?)%>/g,
            interpolate : /<%=([\s\S]+?)%>/g,
            escape      : /<%-([\s\S]+?)%>/g
        };

        // When customizing `templateSettings`, if you don't want to define an
        // interpolation, evaluation or escaping regex, we need one that is
        // guaranteed not to match.
        var noMatch = /(.)^/;

        // Certain characters need to be escaped so that they can be put into a
        // string literal.
        var escapes = {
            "'":      "'",
            '\\':     '\\',
            '\r':     'r',
            '\n':     'n',
            '\u2028': 'u2028',
            '\u2029': 'u2029'
        };

        var escaper = /\\|'|\r|\n|\u2028|\u2029/g;

        var escapeChar = function(match) {
            return '\\' + escapes[match];
        };

        // JavaScript micro-templating, similar to John Resig's implementation.
        // Underscore templating handles arbitrary delimiters, preserves whitespace,
        // and correctly escapes quotes within interpolated code.
        // NB: `oldSettings` only exists for backwards compatibility.
        _.template = function(text, settings, oldSettings) {
            if (!settings && oldSettings) settings = oldSettings;
            settings = _.defaults({}, settings, _.templateSettings);

            // Combine delimiters into one regular expression via alternation.
            var matcher = RegExp([
                (settings.escape || noMatch).source,
                (settings.interpolate || noMatch).source,
                (settings.evaluate || noMatch).source
            ].join('|') + '|$', 'g');

            // Compile the template source, escaping string literals appropriately.
            var index = 0;
            var source = "__p+='";
            text.replace(matcher, function(match, escape, interpolate, evaluate, offset) {
                source += text.slice(index, offset).replace(escaper, escapeChar);
                index = offset + match.length;

                if (escape) {
                    source += "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'";
                } else if (interpolate) {
                    source += "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'";
                } else if (evaluate) {
                    source += "';\n" + evaluate + "\n__p+='";
                }

                // Adobe VMs need the match returned to produce the correct offest.
                return match;
            });
            source += "';\n";

            // If a variable is not specified, place data values in local scope.
            if (!settings.variable) source = 'with(obj||{}){\n' + source + '}\n';

            source = "var __t,__p='',__j=Array.prototype.join," +
                "print=function(){__p+=__j.call(arguments,'');};\n" +
                source + 'return __p;\n';

            try {
                var render = new Function(settings.variable || 'obj', '_', source);
            } catch (e) {
                e.source = source;
                throw e;
            }

            var template = function(data) {
                return render.call(this, data, _);
            };

            // Provide the compiled source as a convenience for precompilation.
            var argument = settings.variable || 'obj';
            template.source = 'function(' + argument + '){\n' + source + '}';

            return template;
        };

        // Add a "chain" function. Start chaining a wrapped Underscore object.
        _.chain = function(obj) {
            var instance = _(obj);
            instance._chain = true;
            return instance;
        };

        // OOP
        // ---------------
        // If Underscore is called as a function, it returns a wrapped object that
        // can be used OO-style. This wrapper holds altered versions of all the
        // underscore functions. Wrapped objects may be chained.

        // Helper function to continue chaining intermediate results.
        var result = function(obj) {
            return this._chain ? _(obj).chain() : obj;
        };

        // Add your own custom functions to the Underscore object.
        _.mixin = function(obj) {
            _.each(_.functions(obj), function(name) {
                var func = _[name] = obj[name];
                _.prototype[name] = function() {
                    var args = [this._wrapped];
                    push.apply(args, arguments);
                    return result.call(this, func.apply(_, args));
                };
            });
        };

        // Add all of the Underscore functions to the wrapper object.
        _.mixin(_);

        // Add all mutator Array functions to the wrapper.
        _.each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
            var method = ArrayProto[name];
            _.prototype[name] = function() {
                var obj = this._wrapped;
                method.apply(obj, arguments);
                if ((name === 'shift' || name === 'splice') && obj.length === 0) delete obj[0];
                return result.call(this, obj);
            };
        });

        // Add all accessor Array functions to the wrapper.
        _.each(['concat', 'join', 'slice'], function(name) {
            var method = ArrayProto[name];
            _.prototype[name] = function() {
                return result.call(this, method.apply(this._wrapped, arguments));
            };
        });

        // Extracts the result from a wrapped and chained object.
        _.prototype.value = function() {
            return this._wrapped;
        };
    }.call(this));

});